Consumer activism has shifted from the margins of market action to the centre of contemporary sustainable governance, serving as an informal but vital mechanism of corporate accountability for environmental, social and ethical practices. In this chapter, I explore the political and ethical significance of everyday consumption in digitally networked economies where formal regulation can all too often fail to keep pace with corporate malfeasance. In this book chapter, we do not consider consumer activism as a single phenomenon, but three working logics that operate simultaneously. Exit-based activism refers to the use of punitive withdrawal strategies such as boycotts, anti-consumption and brand avoidance to impose material and reputational costs on offending companies. Voice-based activism can turn moral outrage into discursive leverage via digital platforms, petitions and collective mobilization to transform personal grievances into collective action. Loyalty-based activism turns these principles upside down, directing purchasing power to companies whose actions align with the ethical values of their customers. This leads to a green brand advocacy which supports value matching corporate behavior. The three modes share a common theoretical basis in signaling theory, social identity theory, social exchange theory, and the value-translation paradigm, but they differ in the behavioral patterns in which the paradigm manifests itself in response to antecedent contexts. The chapter argues that consumer activism is not a substitute but a complement to formal regulation. The continuing attitude-behaviour gap and the structural effects of cost, convenience and habit constrain the ability of market forces to substitute institutional regulation. Mutually limiting arrangements between consumers, corporations and policymakers might collectively increase transparency, mitigate greenwashing and enable long-term commitments that no single entity can maintain on its own. The chapter ends with implications for management practice, focusing on authenticity and dialogic interaction, and for policy design, focusing on transparency regimes, consumer education and incentive structures to convert diffuse consumer demand into systemic results.